Subject: Re: [vserver] vhashify not working? - 2.6.27.14-vs2.3.0.36.4
From: Christoph Lukas <christoph.lukas@gmx.net>
Date: Tue, 31 Mar 2009 14:02:57 +0000


[..]

> > Thank you, Christoph.  The commands show plenty of both types of files
> > > with the hard links clearly outweighing the regular files.  Strange that
> > > I still show 20GB for 10 servers.  Take care - John
> > 
> > Are you sure that your measurements of disk usage are correct?
> > Do the 20 GB disk usage correspond with the df output on the /vservers
> > partition?
> > 
> > du -sch /vservers/*
> > 
> > should notice multiple hardlinks and count them only once.
> > 
> > Regards,
> > Christoph
> > 
> > 
> Yes, the numbers match and they also match the size of the space
> consumed on the thinly provisioned ZFS zvol on which they reside (28.1
> GB):
> [root@vd01 ~]# du -sch /vservers/*
> 4.4G    /vservers/cle
> 2.2G    /vservers/gssstation
> 2.2G    /vservers/jasstation
> 1.4G    /vservers/jintra
> 16K     /vservers/lost+found
> 1.4G    /vservers/mintra
> 1.4G    /vservers/mlapo
> 1.4G    /vservers/simple
> 1.4G    /vservers/smcc
> 1.4G    /vservers/tkee
> 1.4G    /vservers/tvan
> 1.4G    /vservers/vdb
> 1.9G    /vservers/vdb2
> 1.4G    /vservers/vde
> 1.1M    /vservers/vetc
> 23G     total
> 
> I am guessing this may also affect my memory usage.  Does VServer use
> the hashify information to determine whether a binary being called into
> memory already exists? Thanks - John

After unification identical binaries in different vservers are hardlinks
to the same inode. Therefore they are the same file / binary from a
kernel perspective and can reuse cache and memory.

If your memory usage will be lower with unification depends on if all
the running binaries are unified or not.

Regards,
Christoph